Working around "Cannot create an object of type 'System.Boolean' from its string representation" - Init

<body> <h1>Working around "Cannot create an object of type 'System.Boolean' from its string representation"</h1> <div id="codeSnippetWrapper"> In ASP.NET Web Forms most times there’s a need to set ASP.NET Server Control properties at runtime. This, for instance: </div> <span class="pun"> <div id="codeSnippetWrapper"> <div id="codeSnippetWrapper"> <pre style="line-height: 12pt; background-color: #f4f4f4; margin: 0em; width: 100%; font-family: 'Courier New', courier, monospace; color: black; font-size: 8pt; overflow: visible; border-style: none; padding: 0px"> <span style="color: #0000ff"><</span><span style="color: #800000">asp:Button</span> <span style="color: #ff0000">runat</span><span style="color: #0000ff">="server"</span> <span style="color: #ff0000">id</span><span style="color: #0000ff">="Button1"</span> <span style="color: #ff0000">visible</span><span style="color: #0000ff">="true"</span> <span style="color: #0000ff">/></span> </pre> <br /> </div> </div> </span> <p> <span class="pln">It is pretty straightforward to set the value of the visible-property in a code-behind page, like so:</span> </p> <div id="codeSnippetWrapper"> <pre style="line-height: 12pt; background-color: #f4f4f4; margin: 0em; width: 100%; font-family: 'Courier New', courier, monospace; color: black; font-size: 8pt; overflow: visible; border-style: none; padding: 0px"> <span style="color: #0000ff">protected</span> <span style="color: #0000ff">void</span> Page_Load(<span style="color: #0000ff">object</span> sender, EventArgs e) { Button1.Visible = <span style="color: #0000ff">false</span>; } </pre> <br /> </div> <p> <span class="pln">However, it would be nice if you could to things like this</span> </p> <div> <div id="codeSnippetWrapper"> <div id="codeSnippetWrapper"> <pre style="line-height: 12pt; background-color: #f4f4f4; margin: 0em; width: 100%; font-family: 'Courier New', courier, monospace; color: black; font-size: 8pt; overflow: visible; border-style: none; padding: 0px"> <span style="color: #0000ff"><</span><span style="color: #800000">asp:Button</span> <span style="color: #ff0000">runat</span><span style="color: #0000ff">="server"</span> <span style="color: #ff0000">id</span><span style="color: #0000ff">="Button1"</span> <span style="color: #ff0000">visible</span>='<% =<span style="color: #ff0000">User</span>.<span style="color: #ff0000">IsInRole</span>(<span style="color: #0000ff">"Editor"</span>)%>' <span style="color: #0000ff">/></span> </pre> <br /> </div> </div> </div> <div> One might expect that that the expression above is evaluated such that the visible-property is true when the current User has the role of Editor and false if not. Unfortunately, executing this bit results in an exception: </div> <div> <pre class="csharpcode"> <font face="courier new,courier">Cannot create an <span class="kwrd">object</span> of type <span class="str">'System.Boolean'</span> from its <span class="kwrd">string</span> representation <span class="str">'<%= User.IsInRole("Editor") %>'</span> <span class="kwrd">for</span> the <span class="str">'Visible'</span> property. </font> </pre> </div> <div> These problems are discussed also <a href="http://stackoverflow.com/questions/370201" target="_blank">here</a> and <a href="http://stackoverflow.com/questions/370201" target="_blank">here</a>. The reason is that the string-value of each property on a server-control is evaluated and parsed to its desired type. So you could set the property to "True" or "true", but not to an expression that needs to be evaluated. </div> <div> The solution is to use a databinding syntax, which is pretty easy to do </div> <div> <div id="codeSnippetWrapper"> <pre style="line-height: 12pt; background-color: #f4f4f4; margin: 0em; width: 100%; font-family: 'Courier New', courier, monospace; color: black; font-size: 8pt; overflow: visible; border-style: none; padding: 0px"> <span style="color: #0000ff"><</span><span style="color: #800000">asp:Button </body>